3 files changed, 16 insertions, 56 deletions

diff --git a/src/lib/libcrypto/ec/ec_lib.c b/src/lib/libcrypto/ec/ec_lib.c
index 03c6f3aa90..170bdedc57 100644
--- a/src/lib/libcrypto/ec/ec_lib.c
+++ b/src/lib/libcrypto/ec/ec_lib.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ec_lib.c,v 1.95 2025/01/06 10:56:46 tb Exp $ */
+/* $OpenBSD: ec_lib.c,v 1.96 2025/01/06 11:59:02 tb Exp $ */
 /*
  * Originally written by Bodo Moeller for the OpenSSL project.
  */
@@ -107,8 +107,7 @@ EC_GROUP_new(const EC_METHOD *meth)
                 goto err;
 
         /*
-         * generator and seed are optional. mont_ctx, mont_one are only for
-         * curves using EC_GFp_mont_method()
+         * generator, seed and mont_ctx are optional.
          */
 
         return group;
@@ -131,7 +130,6 @@ EC_GROUP_free(EC_GROUP *group)
         BN_free(group->b);
 
         BN_MONT_CTX_free(group->mont_ctx);
-        BN_free(group->mont_one);
 
         EC_POINT_free(group->generator);
         BN_free(group->order);
diff --git a/src/lib/libcrypto/ec/ec_local.h b/src/lib/libcrypto/ec/ec_local.h
index 2bddaddd8a..1b7ca5b645 100644
--- a/src/lib/libcrypto/ec/ec_local.h
+++ b/src/lib/libcrypto/ec/ec_local.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: ec_local.h,v 1.47 2025/01/06 10:56:46 tb Exp $ */
+/* $OpenBSD: ec_local.h,v 1.48 2025/01/06 11:59:02 tb Exp $ */
 /*
  * Originally written by Bodo Moeller for the OpenSSL project.
  */
@@ -143,7 +143,6 @@ struct ec_method_st {
         int (*field_decode)(const EC_GROUP *, BIGNUM *r, const BIGNUM *a,
             BN_CTX *);
 
-        int (*field_set_to_one)(const EC_GROUP *, BIGNUM *r, BN_CTX *);
         int (*blind_coordinates)(const EC_GROUP *group, EC_POINT *p,
             BN_CTX *ctx);
 } /* EC_METHOD */;
@@ -184,9 +183,8 @@ struct ec_group_st {
         /* Enables optimized point arithmetics for special case. */
         int a_is_minus3;
 
-        /* Montgomery context and values used by EC_GFp_mont_method. */
+        /* Montgomery context used by EC_GFp_mont_method. */
         BN_MONT_CTX *mont_ctx;
-        BIGNUM *mont_one;
 } /* EC_GROUP */;
 
 struct ec_key_st {
diff --git a/src/lib/libcrypto/ec/ecp_methods.c b/src/lib/libcrypto/ec/ecp_methods.c
index 7bdeb351da..2297b07175 100644
--- a/src/lib/libcrypto/ec/ecp_methods.c
+++ b/src/lib/libcrypto/ec/ecp_methods.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ecp_methods.c,v 1.19 2025/01/06 10:56:46 tb Exp $ */
+/* $OpenBSD: ecp_methods.c,v 1.20 2025/01/06 11:59:02 tb Exp $ */
 /* Includes code written by Lenka Fibikova <fibikova@exp-math.uni-essen.de>
  * for the OpenSSL project.
  * Includes code written by Bodo Moeller for the OpenSSL project.
@@ -1003,7 +1003,7 @@ ec_points_make_affine(const EC_GROUP *group, size_t num, EC_POINT *points[],
     BN_CTX *ctx)
 {
         BIGNUM **prod_Z = NULL;
-        BIGNUM *tmp, *tmp_Z;
+        BIGNUM *one, *tmp, *tmp_Z;
         size_t i;
         int ret = 0;
 
@@ -1012,11 +1012,16 @@ ec_points_make_affine(const EC_GROUP *group, size_t num, EC_POINT *points[],
 
         BN_CTX_start(ctx);
 
+        if ((one = BN_CTX_get(ctx)) == NULL)
+                goto err;
         if ((tmp = BN_CTX_get(ctx)) == NULL)
                 goto err;
         if ((tmp_Z = BN_CTX_get(ctx)) == NULL)
                 goto err;
 
+        if (!ec_encode_scalar(group, one, BN_value_one(), ctx))
+                goto err;
+
         if ((prod_Z = calloc(num, sizeof *prod_Z)) == NULL)
                 goto err;
         for (i = 0; i < num; i++) {
@@ -1033,13 +1038,8 @@ ec_points_make_affine(const EC_GROUP *group, size_t num, EC_POINT *points[],
                 if (!bn_copy(prod_Z[0], points[0]->Z))
                         goto err;
         } else {
-                if (group->meth->field_set_to_one != NULL) {
-                        if (!group->meth->field_set_to_one(group, prod_Z[0], ctx))
-                                goto err;
-                } else {
-                        if (!BN_one(prod_Z[0]))
-                                goto err;
-                }
+                if (!bn_copy(prod_Z[0], one))
+                        goto err;
         }
 
         for (i = 1; i < num; i++) {
@@ -1118,13 +1118,8 @@ ec_points_make_affine(const EC_GROUP *group, size_t num, EC_POINT *points[],
                 if (!group->meth->field_mul(group, p->Y, p->Y, tmp, ctx))
                         goto err;
 
-                if (group->meth->field_set_to_one != NULL) {
-                        if (!group->meth->field_set_to_one(group, p->Z, ctx))
-                                goto err;
-                } else {
-                        if (!BN_one(p->Z))
-                                goto err;
-                }
+                if (!bn_copy(p->Z, one))
+                        goto err;
                 p->Z_is_one = 1;
         }
 
@@ -1458,9 +1453,6 @@ ec_mont_group_clear(EC_GROUP *group)
 {
         BN_MONT_CTX_free(group->mont_ctx);
         group->mont_ctx = NULL;
-
-        BN_free(group->mont_one);
-        group->mont_one = NULL;
 }
 
 static int
@@ -1478,11 +1470,7 @@ ec_mont_group_copy(EC_GROUP *dest, const EC_GROUP *src)
                 if (!BN_MONT_CTX_copy(dest->mont_ctx, src->mont_ctx))
                         goto err;
         }
-        if (src->mont_one != NULL) {
-                dest->mont_one = BN_dup(src->mont_one);
-                if (dest->mont_one == NULL)
-                        goto err;
-        }
+
         return 1;
 
  err:
@@ -1498,7 +1486,6 @@ ec_mont_group_set_curve(EC_GROUP *group, const BIGNUM *p, const BIGNUM *a,
     const BIGNUM *b, BN_CTX *ctx)
 {
         BN_MONT_CTX *mont = NULL;
-        BIGNUM *one = NULL;
         int ret = 0;
 
         ec_mont_group_clear(group);
@@ -1510,16 +1497,8 @@ ec_mont_group_set_curve(EC_GROUP *group, const BIGNUM *p, const BIGNUM *a,
                 ECerror(ERR_R_BN_LIB);
                 goto err;
         }
-        one = BN_new();
-        if (one == NULL)
-                goto err;
-        if (!BN_to_montgomery(one, BN_value_one(), mont, ctx))
-                goto err;
-
         group->mont_ctx = mont;
         mont = NULL;
-        group->mont_one = one;
-        one = NULL;
 
         ret = ec_group_set_curve(group, p, a, b, ctx);
         if (!ret)
@@ -1527,7 +1506,6 @@ ec_mont_group_set_curve(EC_GROUP *group, const BIGNUM *p, const BIGNUM *a,
 
  err:
         BN_MONT_CTX_free(mont);
-        BN_free(one);
 
         return ret;
 }
@@ -1576,19 +1554,6 @@ ec_mont_field_decode(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
         return BN_from_montgomery(r, a, group->mont_ctx, ctx);
 }
 
-static int
-ec_mont_field_set_to_one(const EC_GROUP *group, BIGNUM *r, BN_CTX *ctx)
-{
-        if (group->mont_one == NULL) {
-                ECerror(EC_R_NOT_INITIALIZED);
-                return 0;
-        }
-        if (!bn_copy(r, group->mont_one))
-                return 0;
-
-        return 1;
-}
-
 static const EC_METHOD ec_GFp_simple_method = {
         .field_type = NID_X9_62_prime_field,
         .group_copy = ec_group_copy,
@@ -1647,7 +1612,6 @@ static const EC_METHOD ec_GFp_mont_method = {
         .field_sqr = ec_mont_field_sqr,
         .field_encode = ec_mont_field_encode,
         .field_decode = ec_mont_field_decode,
-        .field_set_to_one = ec_mont_field_set_to_one,
         .blind_coordinates = ec_blind_coordinates,
 };